Circuit interrupters



A. BACHMAN CIRCUIT INTERRUPTERS Filed Sept.

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ATTOR/Vf/ 3,268,681 Ice Patented August 23, 1966 3,268,681 CIRCUIT INTERRUPTERS Anatole Bachman, Willowdale, Ontario, Canada, assignor to Federal Pacific Electric Company, a corporation of Delaware Filed Sept. 4, 1964, Ser. No. 394,521

14 Claims. (Cl. 200-68) This invention relates to circuit interrupters and more particularly to switches of the type which are used for controlling low voltage industrial power distribution and secondary network circuits.

Switches of this type must necessarily be capable of sustaining relatively high transient currents such as those encountered in the starting of motors and similar devices having high momentary power demands. These momentary polwer demands are nominally several times the noranal current rating of the switch yet are an inherent part of the operating mode of the associated device.

It is an object of this invention to provide a circuit interrupter which is capable of carrying momentary overloads in excess of its normal operating rating without deleterious efiects.

It is yet another object of this invention to provide a circuit interrupter having improved operating characteristics at high current levels.

It is an object of this invention to provide a circuit interrupter of compact configuration which utilizes a minimum number of parts and which is adapted for simplitfied production. 7

An ancillary object of the invention is to provide a circuit interrupter of compact proportions.

These and other objects will be made more apparent by reference to the following drawings taken in conjunction with the accompanying description of a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a side elevational view of the presently preferred embodiment of the invention with some portions broken away or omit-ted and with other parts in section in the interest of clarity;

'FIG. 2 is a plan view on slightly enlarged scale of a portion of the embodiment in FIG. 1 viewed in the direction of the arrow 2 in FIG. 1;

FIG. 3 is a plan View, on an enlarged scale of the contact arm pivot-fuse clip of the embodiment of FIG. 1 as viewed in the direction of the arrow 3 in FIG. 1;

FIG. 4 is a rear elevational view of the portion of the contact arm pivot-fuse clip shown in FIG. 3 as viewed along the line 4-4 of FIG. 3; and

FIG. 5 is a view of a portion of the apparatus of FIG. 1 as viewed along the line 5-5 of FIG. 1 showing the support for the operating crank and the connection between the operating crank and the contact arm.

Referring now to the drawings, the illustrative, presently preferred embodiment of the invention shown in the drawings comprises a m-ul-ti-pole switch which is provided with a base 12 of insulation having a plurality of upstanding pole space defining walls. In the three phase switch illustrated the switch operating means 1 6 is mounted on and secured by screws 17 to the upper surfaces cf the interior pair of walls 14 that delimit the center pole space. The operating means includes a twist handle 18 and a snap-acting overcentering mechanism 20 (not shown in detail) operated by the handle 18. An illustrative overcen-tering mechanism is shown and describe-d in detail in my copending application entitled Circuit Interrupter Serial No. 394,474 filed September 4, 1964, which is assigned to the same assignee as the present invention. Twist handle 18 is pivotally mounted on the cover plate 22, that contains the over-centering mechanism 20, for movement between on and off positions about an axis which is perpendicular to the plane of the base 12.

In the three pole switch shown in the drawing a plurality of isolated pole spaces, each having its own circuit making and breaking components mounted therein, are provided. The upstanding walls define three poles each of which is identically equipped with a pivoted contact arm, associated stationary contact, and means for interconnecting the contact arm and the snap-acting operating mechanism. Since the poles are identical only one will be described in detail.

Referring now to FIG. 1 the contact arm 24 is pivotally mounted at 26 on a combined pivot and fuse clip 28 for movement between a closed circuit and open circuit position in response to operation of the overcentering mechanism 20. Movable contact element 30 is secured to the contact arm adjacent its free end and the companion stationary main contact 32 is secured to a conductor plate 34 fixed to the base 12 by suitable means. In the closed circuit condition of the switch, illustrated in FIG. 1, the contacts 30, 32 meet in substantially face-to-face or butt type engagement with the tangent to their engaged surface forming an angle with the longitudinal axis of the arm 24. The free end 36 of the contact arm 24 is adapted to act as a supplementary contact for engagement with shunt contact means 38 secured to plate 34 adjacent to but spaced from the stationary main contact 32. A conventional line terminal 40 is secured to plate 34 at the end of the pole space. In the closed position of the contact arm the current path through the pole is substantially in a straight line, as follows, to minimize the blow-01f effect produced by high current flow through the path: Through the terminal 40 to plate 3 4, main contacts 30, 32, contact arm 24, pivot 26, and thence through the combined pivot and fuse clip 28 to the fuse terminal blade 42 shownin phantom in FIG. 1. The remote end of the fuse engages a conventional blade type fuse clip (not shown) for subsequent connection to the associated load terminal.

An arc chute 44 is mounted in the pole space adjacent the companion contacts 30, 32 and shunt contact means 38. The are chute includes a plurality of spaced metal plates 46 secured to an insulator 48 and functions in a well-known manner to produce arc extinction when the contacts are separated under load.

Referring to FIGS. 1, 3 and 4, the combination contact arm pivot-fuse clip or support 28 will be described in detail. The support 28 includes a fixed member 50 secured to base 12 and a movable member 52 that lie in substantially parallel planes. Fixed member 50 is attached to the base by screws that pass through an offset portion 54 which passes beneath the movable member 52. Members 50 and 52 are provided with opposed inclined surfaces 56 for initially engaging and guiding the fuse blade 42. In the fully inserted position the fuse blade is gripped between their opposed planar surfaces 58. Movable member 52 is coupled to the fixed member 50 by means of a T-shaped retainer 60 that extends through appropriate openings formed in the plates 50, 52. The head 60a of the retainer engages the movable member and the tail 60b engages contact pressure spring 62 mounted in a stressed condition between the peened end of the tail and movable member 50. Spring 62 biases the members 50, 52 together. Each of the members 50, 52 is provided with an embossed ring-shaped portion 64, 68 respectively, which cooperate to provide the bearing surfaces at the pivot 26 for the contact arm. Contact pressure between the contact arm and the opposed faces of the members 50, 52 at the pivot 26 is produced by the spring 62, the contact arm being interposed between the members. Both the members 50, 52 and the contact arm are silver plated to minimize contact resistance. In order to limit the inward movement of the movable member 52 when a fuse is not present and to provide reaction point for the generation of the contact pressure, a spacer 66 is struck up from the fixed member 50. The spacer 66 has an end portion 68 that extends through an aperture formed in the movable member 52 and shoulders 70 against which the member 52 is arrested. A lanced-out stop 72 provides an additional stop to limit the inward movement of the movable member 52. The non-fused separation between the members 50, 52 is less than the thickness of the fuse blade 42. When no fuse is present between the members 50, 52 the stop 72, spacer 66 and pivot 26 have a triangular configuration and the force of spring 62 is effective to produce contact pressure between the contact arm and members 50, 52 at the pivot. When a fuse terminal is inserted between the members 50, 52 they are driven apart so that neither the stop 72 or spacer 66 is operative and the displacement of member 52 with respect to member 50 serves to increase the contact pressure at the pivot 26 by further stressing the spring 62 as the movable member 52 rocks with respect to the base member 50.

Referring to FIGS. 1 and 5, a formed operating crank 74 is shown which spans the three poles and joins the contact arms 24 to the overcentering mechanism 20 for simultaneous movement between the open circuit and closed circuit positions. Crank 74 has what may be considered a serpentine configuration lying substantially in one plane but for an end 74a which is formed to engage the overcentering mechanism 20. Referring particularly to FIG. crank 74 has a pair 'of bearing portions 74b (only one shown) that are carried within notches having bearing surfaces 76 on the interior walls 14 of the casing 12. The crank is retained in the notches by brackets 78 carried on the underside of the cover plate 22 (FIG. 1). The crank has other portions 740 adapted to be engaged by link 80 that connects the individual contact arms 24 to the crank.

Since the links 80 are identical only one will be described in detail. Link 80 includes two pieces of formed insulation 82, 84 positioned on opposite sides of the contact arm and joined together by a pivot pin 86. Pin 86 passes through an aperture 88 provided in the contact arm and pivotally secures the two side plates 82, 84 to one another on opposite sides of the contact arm. Aperture 88 has a notch 88a to position the pin 86 and a contiguous rectangular portion 88b to receive a spring 90. Spring 90 is a laminated leaf spring and interposed between the pivot pin and the contact arm. The spring is retained in its protected position within the planes defined by the opposed broad surfaces of the contact arm by the depending portions of the plates 82, 84 forming the link 80. At their remote ends, adjacent the crank portion 740, the plates 82, 84 provide oppositely facing notches 92, 94 respectively, which embrace the crank forming a pivotal connection thereon. In order to maintain the plates parellel to one another, the ends of the plates 82, 84 adjacent the crank are spaced from one another and secured together by a cross member 96. The cross member 96 rests in notches 98 formed in the top surfaces of the plates, as viewed in FIG. 1, and ends of the member engage the outer broad faces of the plates. A pair of depending tabs 100 on member 96 are interposed between the plates and maintain their separation. Retention of cross member 96 in the plates is provided by screw 102 that engages a threaded part 104 that extends through the plates. The construction outlined above results in the formation of a rigid link pivoted to the contact arm and to the operating crank at its ends. Utilizing this form of construction the crank may be positioned in the notches in the walls 14 and the links 24 may then be assembled as by swinging the respective plates 82, 84 into position with the crank portion 740 received in the notches 92, 94 formed therein. The plates 82, 84 are then secured together by the cross member 96 so that the crank is pivotally secured.

The shunt contact means 38, shown in detail in FIG. 2,

is connected electrically and mechanically to plate 34. The shunt contact means includes a U-shaped member 106 to which are connected a pair of opposed depending arms 108, 110. The arms 108, 110 are attached to remote face of the bight portion of member 106 and are looped so that they pass between the legs of member 106 to engage the end 36 of the cont-act arm, with a lateral wiping action, at the front of member 106. The free ends of the arms 108, 110 are beveled at 112 to diverge outwardly for receiving the end of the contact arm therebetween. The arms 108, 110 are biased toward one another by a hairpin shaped spring 114 which provides contact pressure. Arms 108, 110 are spaced from one another by an interposed insulator 116 and spring 114 is retained in position by passing through an aperture 118 in the insulation. Insulator 116 is maintained in position by cooperation with inwardly directed projections 120 on each of the arms 108, 110. The lateral engagement of the arms 108, 110 with the contact arm is such that contact is maintained with the contact arm during a portion of the movement of the contact arm with respect to the stationary contact 32. The arms 108, 110 also serve as the arcing contacts for the switch when it is completely opened under load. The are is drawn into the arc chute 44 and is there extinguished in a manner well known in the art.

The aforedescribed embodiment of the invention is assembled in the following manner. The conductor plate 34 carrying the stationary contact 32 and the shunt contact means 38 is mounted in the casing 12. Then the subassembly, comprising the contact arm 24 and the combined pivot and fuse clip 28 together with the pivoted plates 82, 84, to form link 80, is secured in position. Next the arc chute 44 is mounted adjacent the main contacts. Subsequently the operating crank 74 is dropped into position in the notches in the casing Walls 14 andthe plates 82, 84 are swung up to engage the crank portions 74c from opposite sides. Cross members 96 are attached and connected to the plates completing the links 80. Finally the operating mechanism 16 that carries twist handle 18 and the overcentering means 20 is attached to the casing with the crank end 740 received by the overcentering means. It will be seen from the foregoing that the entire assembly operation, as described, may be easily performed from top of the casing with all of the components stacking together readily.

The mode of operation of the switch will be best understood from the following description. When the twist handle is shifted from its off position to the on position shown in FIG. 1, the overcentering means 20 operates with a snap action and drives the crank 74 clockwise about its hearings in the walls 14. The movement of the crank is translated into counterclockwise movement of the contact arms 24 about their pivots 26 from the open circuit position to the closed circuit position. The main contacts 30, 32 engage before the end of the operating stroke of the crank and its continued movement causes the links to drive the pivot pins 86 against the springs thus building up contact pressure. The contact pressure is maintained by overcentering means 20 which urges the crank further clockwise. The angle formed by the plane of the crank and the longitudinal axis of the links 80 is small so that the mechanism is able to resist blow off separation of the contacts. When the twist handle is moved reversely from on to off the overcentering means 20 drives the crank counterclockwise and causes the links 80 to pivot the contact arms 24 away from the stationary contact. The link pivot pins 86 engage the upper surface of the aperture 88 in the contact arm and from a positive connection therewith.

The substantially straight line current path through the switch is designed to minimize contact bounce due to electromagnetic effects when high currents flow through the switch. However, if some bounce should occur during high current flow or during the closing of the switch, the shunt contact means 38 is effective to minimize or eliminate any arcing between the main contacts.

The foregoing specific embodiment of the invention is presently preferred, but it will be apparent to those skilled in the art that features of the invention may be utilized in dilferent applications and in modified form. Therefore, the invention should be broadly construed in accordance with its full spirit and scope.

I claim:

1. A circuit interrupter including a base of insulation, a pair of companion butt contacts including a stationary contact mounted on said base and a movable contact, a contact arm, said movable contact being mounted on said contact arm for movement between open circuit and closed circuit positions, shunt contact means electrically connected to said stationary contact and mounted on said base for lateral wiping engagement with said contact arm in said closed circuit position, means mounting said contact arm on said base, said mounting means including a first member secured to said base and a second member coupled with said first member and movable relative thereto, said first and second members receiving said contact arm therebetween and having formed portions providing pivotal bearing surfaces for said contact arm and other adjacent portions for providing surface-to-surface contact with said arm, means biasing said first and second members together to provide contact pressure with said contact arm, operating means for said contact arm, and means coupling said operating means to said contact thereto, said first and second members receiving said arm, said coupling means including a link pivoted to said link and said contact arm, said resilient means providing contact pressure between said companion contacts in the closed circuit position.

2. A circuit interrupter including a base of insulation, a pair of companion contacts including a stationary contact mounted on said base and a movable contact, a contact arm, said movable contact being mounted on said contact arm for movement between open circuit and closed circuit positions, means pivotally mounting said contact arm on said base, said mounting means including a first member secured to said base and a second member coupled to said first member and movable relative thereto, said first and second member receiving said contact arm therebetween and having formed portions providing pivotal bearing surfaces for said contact arm and other portions for providing surface-to-surface contact with said arm, said first and second members having cooperating portions formed to provide a fuse terminal receiving means, means biasing said first and second members together to provide contact pressure with said contact arm and a fuse terminal received therebetween, operating means for said contact arm, and means coupling said operating means to said contact arm, said coupling means including a link pivoted to said contact arm, and resilient means interposed between said link and said contact arm, said resilient means providing contact pressure between said companion contacts in the closed circuit position.

3. A circuit interrupter including a casing of insulation, a pair of companion contacts including a stationary contact mounted in said casing and a movable contact, a contact arm, said contact arm having parallel broad faces and narrow faces perpendicular thereto, said movable contact being mounted on a narrow face of said contact arm for movement between open circuit and closed circuit positions, means pivotally mounting said contact arm in said casing for swinging movement with the broad faces of said contact arm parallel to the plane of movement, operating means for said contact arm, and means coupling said operating means to said contact arm, said coupling means including a link pivoted to said contact arm, and resilient means interposed between said link and said contact arm, said resilient means being positioned entire- 1y within the space defined by said broad faces and said narrow faces of said contact arm, said resilient means providing contact pressure between said companion contacts in the closed circuit position.

4. A circuit interrupter according to claim 3 wherein said resilient means is a laminated leaf spring.

5. A circuit interrupter according to claim 3 wherein said link has portions extending along each of said broad faces of said contact arm for retaining said resilient means within said contact arm.

6. A circuit interrupter according to claim 3 wherein said coupling means is a crank pivoted in said casing and said link is a two part member, one part of said link being mounted adjacent each of said broad faces of said contact arm respectively by a pivot pin, said link parts embracing said crank from opposite sides thereof to thereby form a pivotal connection thereto, and means removably securing said link parts together adjacent said crank.

7. Circuit interrupter including a casing of insulation, a stationary contact mounted in said casing and a companion movable contact, said movable contact being mounted on a contact arm for movement between open and closed circuit positions, means mounting said contact arm in said casing, operating means for said contact arm, and means coupling said operating means to said contact arm, said coupling means including a link pivoted to said contact arm, a pivot pin for connecting said link to said contact arm, said contact arm being formed to provide an aperture in said contact arm for receiving said pivot pin, spring means in said aperture interposed between one side of said pivot pin and said contact arm to provide a resilient connection between said link and said arm, said link having portions cooperating with said contact arm for retaining said spring means in position in said aperture, said spring means providing contact pressure between said companion contacts in the closed circuit position.

8. A circuit interrupter including a base of insulation, a pair of companion butt contacts including a stationary contact mounted on said base and a movable contact, a contact arm, said movable contact being rigidly mounted on said contact arm for movement between open circuit and closed circuit positions, operating means for moving said contact arm, means coupling said operating means to said contact arm, resilient means interposed between said coupling means and said contact arm, an arc chute including metal arc splitter plates, said arc chute being mounted adjacent stationary contact, said movable contact passing through said are chute when moved between said open circuit and closed circuit positions, and shunt contact means electrically connected to said stationary contact and mounted on said base external to and adjacent said arc chute for lateral wiping engagement with said contact arm.

9. A circuit interrupter including a base of insulation, a pair of companion butt contacts including a stationary contact mounted on said base and a movable contact, a contact arm, said movable contact being rigidly mounted on said contact arm for movement between open circuit and closed circuit positions, operating means for moving said contact arm, means coupling said operating means to said contact arm, resilient means interposed between said coupling means and said contact arm, an arc chute including metal are splitter plates and a supporting insulator, said are chute being mounted adjacent said stationary contact, said movable contact passing through said arc chute when moved between said open circuit and closed circuit positions, and shunt contact means electrically connected to said stationary contact, means mounting said shunt contact means on said base external to and adjacent said are chute, said arc chute insulator being interposed between said mounting means and the path of movement of said movable contact, said shunt contact means having a portion adjacent said stationary contact for lateral wiping engagement with said contact arm.

10. A circuit interrupter including a base of insulation, a pair of companion butt contacts including a stationary contact and a movable contact, a conductor platesecured to said base, said stationary contact being mounted on said conductor plate, a contact arm pivotally mounted on said base, said movable contact being rigidly mounted on said contact arm for movement between open circuit and closed circuit positions, operating means for moving said contact arm, means coupling said operating means to said contact arm, resilient means interposed between said coupling means and said contact arm, said conductor plate, said companion butt contacts and said contact arm being arranged to provide a substantially straight line current path therethrough, and shunt contact means electrically connected to said conductor plate and mounted on said base for lateral wiping engagement with said contact arm in said closed circuit position.

11. A circuit interrupter according to claim 8 wherein said shunt contact means includes a pair'of opposed arms for receiving said contact arm therebetween, means biasing said arms toward one another, and means positioned between said arms for limiting their movement toward one another and to thereby determine the initial bias of said arms against said contact arm.

12. A circuit interrupter according to claim 9 wherein said shunt contact means includes a pair of opposed arms for receiving said contact arm therebetween, means biasing said arms toward one another, and means positioned between said arms for limiting their movement toward one another, said biasing means being shielded from the arc space by said arms and said limiting means.

13. A circuit interrupter according to claim 9 wherein said shuntcontact means includes a U-shaped member external to said are chute, said U-shaped member having a pair of legs interconnected by -a bight portion, said .U- shaped member having one face thereof toward said are chute, a pair of opposed depending arms connected to said bight portion on the opposite face of said U-shaped member, said arms being looped so that they pass between the legs of said U-shaped member to a position within said are chute adjacent said stationary contact for lateral wiping engagement with said contact arm.

14. A circuit interrupter according to claim 6 wherein said link parts are formed of electrical insulation material.

References Cited by the Examiner UNITED STATES PATENTS Re.22,218 11/1942 Von Hoorn 200-116 1,210,581 1/1917 Anderson 200146 2,802,922 8/1957 Page et al. 3,076,882 2/1963 Judd et al 200-146 ROBERT K. SCHAEFER, Primary Examiner. KATHLEEN H. CLAFFY, Examiner. D. SMITH, JR., Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,268,681 August 23, 1966 Anatole Bachman It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 31, strike out "thereto, said first and second members receiving said"; line 32 after "said", second occurrence, insert contact arm, and resilient means interposed between said Signed and sealed this lst day of August 1967.

(SEAL) Attest:

Edward M. Fletcher, I r.

kttesting Officer EDWARD J. BRENNER Commissioner of Patents 

1. A CIRCUIT INTERRUPTER INCLUDING A BASE OF INSULATION, A PAIR OF COMPANION BUTT CONTACTS INCLUDING A STATIONARY CONTACT MOUNTED ON SAID BASE AND A MOVABLE CONTACT, A CONTACT ARM, SAID MOVABLE CONTACT BEING MOUNTED ON SAID CONTACT ARM FOR MOVEMENT BETWEEN OPEN CIRCUIT AND CLOSED CIRCUIT POSITIONS, SHUNT CONTACT MEANS ELECTRICALLY CONNECTED TO SAID STATIONARY CONTACT AND MOUNTED ON SAID BASE FOR LATERAL WIPING ENGAGEMENT WITH SAID CONTACT ARM IN SAID CLOSED CIRCUIT POSITION MEANS MOUNTING SAID CONTACT ARM ON SAID BASE, SAID MOUNTING MEANS INCLUDING A FIRST MEMBER SECURED TO SAID BASE AND A SECOND MEMBER COUPLED WITH SAID FIRST MEMBER AND MOVABLE RELATIVE THERETO, SAID FIRST AND SECOND MEMBERS RECEIVING SAID CONTACT ARM THEREBETWEEN AND HAVING FORMED PORTIONS 